Pressure Distributions in a Superlaminar Journal Bearing

1982 ◽  
Vol 104 (2) ◽  
pp. 187-195 ◽  
Author(s):  
J. B. Roberts ◽  
R. E. Hinton
Keyword(s):  
Reynolds Number ◽  
Total Pressure ◽  
Pressure Field ◽  
Journal Bearing ◽  
Pressure Measurements ◽  
Inertial Effects ◽  
Empirical Theory ◽  
Number Range ◽  
Pressure Distributions ◽  
Friction Factors

The main features of a comprehensive set of pressure measurements, obtained from a short, plain journal bearing, are presented. The pressure field in the lubricant film was measured in both the circumferential and axial directions over a Reynolds number range of 40–50,000. In cases where the film is noncavitating the pressure distributions are separated into viscous and inertial components. The inertial components are found to agree fairly well with an approximate short bearing theory. Axially averaged, total pressure distributions are compared with the predictions of a simple, empirical theory based on measured friction factors and incorporating inertial effects.

An Experimental Investigation of Pressure Distributions in a Journal Bearing Operating in the Transition Regime

1986 ◽  
Vol 200 (4) ◽  
pp. 251-264 ◽  
Author(s):  
J B Roberts ◽  
P J Mason
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
Journal Bearing ◽  
Transition Regime ◽  
Pressure Measurements ◽  
Eccentricity Ratio ◽  
Clearance Ratio ◽  
Viscosity Parameter ◽  
Pressure Distributions ◽  
Friction Factors

Experimental results are presented, relating to friction factors and circumferential pressure distributions, for a plain cylindrical journal bearing with a central circumferential inlet groove. The length-diameter ratio of each journal bearing land was 0.25 and the clearance ratio was 0.0031. The friction factor results showed the existence of a distinct ‘transition regime’, characterized by a pronounced ‘hump’ in the friction factor-Reynolds number relationship. Pressure measurements recorded when operating in this transition regime revealed the inadequacy of many existing ‘turbulent’ theories for superlaminar lubrication. By using a short-bearing theory a good correlation of the pressure distribution results was obtained, in terms of a non-dimensional viscosity parameter, kz, which is dependent on both the eccentricity ratio and Reynolds number. The magnitude of kz in this regime was considerably higher than the corresponding value for laminar flow, and was similar to the magnitude predicted from a simple theory based on relating kz to the variation of measured friction factor with Reynolds number.

Flow field behind a complex total pressure distortion screen

2019 ◽  
Vol 233 (14) ◽  
pp. 5075-5092
Author(s):  
M Sivapragasam
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Design Methodology ◽  
Pressure Field ◽  
Alternative Interpretation ◽  
Interface Plane ◽  
Screen Design ◽  
Pressure Distributions ◽  
Water Jet Cutting ◽  
Distortion Index

The flow field behind a complex total pressure distortion screen is investigated experimentally and numerically. The distortion screen is designed using an established design methodology and fabricated by water-jet cutting technique. The distorted total pressure field behind the screen is quantified by a distortion index parameter, which is evaluated from computations and experiments for several values of inlet Mach number. The root-mean-square error between the target total pressure values and that achieved by the screen design at the aerodynamic interface plane is 4.75%. The evolution of the distorted total pressure field downstream of the screen is presented in detail in terms of radial and circumferential total pressure distributions and their gradients. An alternative interpretation of the distorted total pressure field is made by means of defining a total pressure flux existing behind the screen and expanding it using derivative-moment transformation technique. It is seen that the circumferential vorticity is a major contributing factor to the total pressure flux.

Empirical Treatment of Hydrodynamic Journal Bearing Performance in the Superlaminar Regime

1970 ◽  
Vol 12 (2) ◽  
pp. 116-122 ◽  
Author(s):  
H. F. Black
Keyword(s):  
Reynolds Number ◽  
Field Equation ◽  
Experimental Work ◽  
Reynolds Equation ◽  
Pressure Field ◽  
Journal Bearing ◽  
Load Capacity ◽  
Journal Bearings ◽  
Theoretical Treatment ◽  
Hydrodynamic Journal Bearing

The application of a perturbation in terms of simple correlations for friction in turbulent Couette and ‘screw’ flows, together with a further empirical assumption consonant with the experimental work of Smith and Fuller (1), leads to a pressure field equation identical in form with the Reynolds equation. The load capacity of journal bearings throughout most of the superlaminar range may be represented by a single curve, and existing laminar solutions may be applied with the parameters modified by Reynolds number. The theory is compared with published experimental results, and with the most successful theoretical treatment (4). The correlations obtained confirm the adequacy of the theory to predict performance in the superlaminar régime.

Numerical Investigation of Impingement Heat Transfer on a Flat and Square Pin-Fin Roughened Plates

2013 ◽  
Author(s):  
Chaoyi Wan ◽  
Yu Rao ◽  
Xiang Zhang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Flat Plate ◽  
Numerical Investigation ◽  
Pressure Loss ◽  
Transfer Characteristic ◽  
Number Range ◽  
Pin Fin ◽  
Pressure Distributions ◽  
Impingement Heat Transfer

A numerical investigation of the heat transfer characteristics within an array of impingement jets on a flat and square pin-fin roughened plate with spent air in one direction has been conducted. Four types of optimized pin-fin configurations and the flat plate have been investigated in the Reynolds number range of 15000–35000. All the computation results have been validated well with the data of published literature. The effects of variation of jet Reynolds number and different configurations on the distribution of the average and local Nusselt number and the related pressure loss have been obtained. The highest total heat transfer rate increased up to 162% with barely any extra pressure loss compared with that of the flat plate. Pressure distributions and streamlines have also been captured to explain the heat transfer characteristic.

Flow Past Circular Cylinder With Different Surface Configurations

1992 ◽  
Vol 114 (2) ◽  
pp. 170-177 ◽  
Author(s):  
Y. C. Leung ◽  
N. W. M. Ko ◽  
K. M. Tang
Keyword(s):  
Reynolds Number ◽  
Groove Surface ◽  
Number Range ◽  
Pressure Distributions ◽  
Downward Shift ◽  
Reynolds Number Range ◽  
Lower Reynolds Number ◽  
Smooth Cylinder ◽  
Mean Pressure ◽  
The Mean

Measurements of the mean pressure distributions and Strouhal numbers on partially grooved cylinders with different groove subtend angles were made over a Reynolds number range of 2.0×104 to 1.3×105 which was within the subcritical regime of smooth cylinder. The Strouhal number, pressure distributions, and their respective coefficients were found to be a function of the groove subtend angles. In general, a progressive shift of the flow regime to lower Reynolds number was observed with higher subtend angle and a subtend angle of 75 deg was found for optimum drag reduction. With the configuration of asymmetrical groove surface, lower drag, and higher lift coefficients were obtained within the same Reynolds number range. Wake traverse and boundary layer results of the asymmetric grooved cylinder indicated that the flows at the smooth and groove surfaces lied within different flow regimes and a downward shift of the wake.

Highly viscous liquid flow in pipeline components

2005 ◽  
Vol 219 (3) ◽  
pp. 267-281 ◽  
Author(s):  
D A McNeil ◽  
A D Stuart
Keyword(s):  
Reynolds Number ◽  
Viscous Liquid ◽  
Liquid Flow ◽  
Flow Behaviour ◽  
Number Range ◽  
Pipe Flows ◽  
Discharge Coefficients ◽  
Friction Factors ◽  
Loss Coefficients ◽  
Globe Valve

Water and an aqueous glycerine solution were used to obtain liquids with nominal viscosities of 1 and 550 mPa s. These fluids were used to obtain friction factors for pipe flows, discharge coefficients for orifice plates and nozzles, and loss coefficients for an abrupt enlargement, a nozzle, an orifice plate, and a globe valve in the Reynolds number range 10-200. Existing methods are shown to be adequate for the prediction of friction factors and discharge coefficients, but inadequate for the prediction of loss coefficients. Insight is given into the flow behaviour that is associated with the loss coefficients.

The Characteristics of a Statically Loaded Journal Bearing with Superlaminar Flow

1980 ◽  
Vol 22 (2) ◽  
pp. 79-94 ◽  
Author(s):  
R. E. Hinton ◽  
J. B. Roberts
Keyword(s):  
Friction Factor ◽  
Journal Bearing ◽  
Load Capacity ◽  
Reynolds Numbers ◽  
Diameter Ratio ◽  
Experimental Results ◽  
Empirical Theory ◽  
Clearance Ratio ◽  
Friction Factors ◽  
Theoretical Predictions

Experimental results are presented, relating to the friction factor, load capacity and attitude angle, for a plain, cylindrical journal bearing with a central, circumferential inlet groove. The length to diameter ratio of the journal bearing was 1/3 and the clearance ratio was 0.011. By the use of various lubricants, including water, Reynolds numbers ranging from 40 to 50 000 were attained. Comparisons with various theoretical predictions are given. It is shown that a simple, empirical theory, which incorporates measured friction factors, gives better agreement with the experimental load capacity results than previous theories.

Heat Transfer and Pressure Drop in a Helically Coiled Rectangular Duct

1986 ◽  
Vol 108 (2) ◽  
pp. 343-349 ◽  
Author(s):  
V. Kadambi ◽  
E. K. Levy ◽  
S. Neti
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Reynolds Numbers ◽  
Rectangular Duct ◽  
Number Range ◽  
Rectangular Wave ◽  
Friction Factors ◽  
Sudden Transition ◽  
The Heat Transfer Coefficient ◽  
Straight Duct

The present paper deals with experiments using air in three helically coiled rectangular ducts of mean diameters 12.7 cm, 17.8 cm, and 22.8 cm, respectively, made of rectangular wave-guide tubing of dimensions 1.27 cm × 0.64 cm. Pressure variations observed around the ducts were qualitatively in agreement with the expectations for secondary flow. The friction factors change gradually with increasing Reynolds numbers over the range 1200–10,000 without exhibiting a sudden transition from laminar flow to turbulence. At all Reynolds numbers, these are higher than those for a straight duct by 20–100 percent. The heat transfer coefficient is also higher than that for straight ducts ranging between 20–300 percent, depending on the Reynolds number. The largest increases are seen in the Reynolds number range 1200–2500.

Steady and Unsteady Surface Pressure Distributions Around Rectangular Prisms With Sharp Edges at Reynolds Number Up to 2.5×106

2006 ◽  
Author(s):  
Annick D’Auteuil ◽  
Guy L. Larose
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Surface Pressure ◽  
Angle Of Attack ◽  
Pressure Measurements ◽  
Oncoming Flow ◽  
Pressure Distributions ◽  
Unsteady Surface Pressure ◽  
Sharp Edges ◽  
Flow Reattachment

The commonly-held assumption that the aerodynamics of rectangular prisms with sharp edges are insensitive to Reynolds number is shown to have limitations. Flow reattachment on the top and/or bottom of the prisms can be related to Reynolds number, Re. Steady and unsteady surface pressure measurements were carried out on nine different rectangular prisms for Re from 0.3×106 to 2.5×106 at several angles of attack, in smooth and turbulent flow. It was observed that the reattachment was dependent on parameters such as fineness ratio, edge treatment, angle of attack, turbulence of the oncoming flow and Reynolds number. Permanent reattachment occurred for prisms with fineness ratio of 4 and fluctuating reattachment took place for rectangular prisms with fineness ratio as low as 2.

The effects of surface roughness on the flow past circular cylinders at high Reynolds numbers

1982 ◽  
Vol 123 ◽  
pp. 363-378 ◽  
Author(s):  
Y. Nakamura ◽  
Y. Tomonari
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
High Reynolds Number ◽  
Circular Cylinders ◽  
Similarity Parameter ◽  
Number Range ◽  
Pressure Distributions ◽  
Mean Pressure ◽  
Supercritical Range ◽  
High Reynolds

Measurements of’ the mean-pressure distribution and the Strouhal number on a smooth circular cylinder, circular cylinders with distributed roughness, and circular cylinders with narrow roughness strips were made over a Reynolds-number range 4.0 × l04 to 1.7 × l06 in a uniform flow. A successful high-Reynolds-number (trans- critical) simulation for a smooth circular cylinder is obtained using a smooth circular cylinder with roughness strips. High-Reynolds-number simulation can only be obtained by roughness strips and not by distributed roughness. A similarity parameter correlating the pressure distributions on circular cylinders with distributed roughness in the supercritical range is presented. The same parameter can also be applicable to the drag coefficients of spheres with distributed roughness.

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